Vacuum-operated load grab



June 20, 1967 FARMER ET AL 3,326,593

VACUUM-OPERATED LOAD GRAB Filed June 5, 1965 Ju 2% g 3 Sfcmlez E. Former cr'r F. Weinerf INVENTORS Mazda 5 W United States Patent 3,326,593 VACUUM-OPERATED LOAD GRAB Stanley E. Farmer and Harry F. Weinert, Portland, 0reg., assignors to Cascade Corporation, Portland, Oreg., a corporation of Oregon Filed June 3, 1965, Ser. No. 460,989 5 Claims. (Cl. 294-64) This invention relates to improvements in vacuum-operated load grab mechanisms, and more particularly to novel structure functioning as a suction cup in such a mechanism through which the mechanism attaches to a load.

Load grabs utilizing suction or vacuum to attach onto a load offer a convenient method of handling loads without the use of pallets. In the handling of such articles as paper rolls, for instance, vacuum-operated attachments are becoming employed increasingly, since such an article has a shape that adapts itself to vacuum handling, and with vacuum-operated load grabs there is much less likelihood of damaging a roll than when clamps are used. In general terms, a load grab of this type which attaches to the side of a load must include means forming one or more suction cups for producing an evacuated zone adjacent the load, and structure whereby with atmospheric pressure pushing the suction cup and load together, friction is established between the load and what forms the suction cup sufficient to enable an upward force to be transmitted to the load from the load grab of sufficient magnitude to counteract the downward force exerted by a suspended load by reason of its mass.

In general terms, an object of this invention is to provide improved means forming a suction cup in a load grab, in the form of a rim extending in a continuous course which defines the open mouth of a suction cup in the device, said rim including both means for producing a vacuum seal with an article or load, and means for frictionally engaging a side of such article whereby the same may be lifted upon such a vacuum seal being produced.

Various forms of suction cups for attaching to a load have been proposed in the past. In some, the means forming the mouth of the cup may take the form of a flexible lip of relatively soft, yielda=ble rubber or other elastomer, such flexibility being selected to enable the lip easily to conform to the shape of the object handled and best to produce the seal desired. A disadvantage of this type of construction is that the lip tends to fold or curl over on itself, during the act of positioning the load grab mechanism against the side of the load, and this curling prevents a seal from being obtained. If the lip is made of stiffer material to obviate this, the lip, because it is less easily conformable to the outside of a load, is best used with only a limited range of load sizes. A feature of this invention, and an object thereof, is the provision of novel means for forming a seal, which is highly efiective in producing a seal, without such tendency to fold or curl over as mentioned, but nevertheless is adapted to handle a relatively wide range of load shapes and sizes.

In a suction cup with a flexible lip defining the mouth opening, when a load is lifted the cup must exert a vertically upward force on the load equal to the downward force resulting from the mass of the load. If the lip of the cup is made of soft, flexible material, the lip has not strength sufficient by itself to exert such a force. Thus, a general practice has been to include some form of friction producing elements inside the mouth opening, which are mounted in a stationary position at the back of the cup. With these elements present, and on a suction produced in the cup, the load presses against the friction elements, and the lip then functions to produce the seal while the friction elements produce the contact with the load by 3,325,593 Patented June 20, 1967 ice which an upward force is transmitted to the load. The inclusion of such friction elements, however, is not altoge'ther satisfactory, since if they are to be used in lifting heavy loads, they must be relatively stiff and nonconforming, which again limits the sizes of loads that can be handled. Further, in many constructions it is difficult to engage frictionally a large area over the side of a load with such a construction.

Another object of the invention, therefore, is to provide novel means defining the open mouth of a suction cup, which includes not only means for forming a seal with a load, but inwardly from this means and as part of the means defining the mouth opening, friction means for frictionally engaging a load with physical properties that enable both heavy and light loads to be picked off the ground.

Yet another object is to provide improved means defining the open mouth of a suction cup, in a vacuum-operated load grab, comprising a casing with side walls attached in a novel manner to a mounting, said casing having 'over the front thereof (that part which actually engages a load) novel means for forming a seal with a load,

and inwardly from this means, means for frictionally engaging a side of a load.

The casing is attached to its mounting in such a manner that it may be subjected to severe stresses without ripping apart or deforming excessively. The casing has suitable yieldability in a direction which may generally be described as normal to the mounting (whereby it can conform to different roll sizes), but is 'braced from movement laterally or substantially parallel to its mounting so that with vacuum applied to the space that the casing surrounds in providing a cup mouth, the casing does not snake or otherwise deform appreciably.

These and other objects and advantages will become more fully apparent as the following description is read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front elevation of a load grab with multiple suction cup assemblies provided therein for attaching to the side of a load;

FIG. 2. is a cross-sectional view, on a somewhat larger scale, through one of the suction cup assemblies in the mechanism shown in FIG. 1;

FIG. 3 is a cross-sectional view, along the line 33 in FIG. 1, on an even larger scale, showing a modified form of the invention; and

FIG. 4 is a view on an enlarge-d scale showing portions of the front of a casing which defines the mouth opening for the suction cup assembly.

Referring now to the drawings, and first of all more particularly to FIGS. 1 and 2, here load grab mechanism is shown such as may be utilized in picking up paper rolls, and provided as an attachment on the vertically movable load-lifting carriage found in a lift truck. The mechanism illustrated comprises six suction cup assemblies 13 mounted on a common equalizer plate 11. The equalizer plate is adapted to be mounted on the carriage of a lift truck or other loading or lifting and carrying device. Since the load grab is intended for use with paper rolls, the equalizer plate may have a slightly curved outline roughly corresponding to the curvature of the rolls handled.

Each suction cup assembly 10 has an elongated resilient rim 14 extending in a continuous course on one side of a mounting plate 16. The mounting plate forms the back of the cup assembly, and rim 14, which throughout its length is raised outwardly from the mounting, extends about and defines the open mouth of the suction cup assembly.

Plate 16 is connected to a heavier support plate 17, and the latter plate is resiliently mounted on equalizer plate 11 common to all the suction cup assemblies by 3 bolts 18 and springs 19. Relative movement between a suction cup assembly and equalizer plate 11 is provided by allowing clearance between conical bosses 20 on the support plate and conical recesses 21 in the equalizer plate, these bosses and recesses being concentric with bolts 18. Springs 19 normally hold the cup spaced as far from the equalizer plate as the bolts 18 will allow, but when the whole assemblage as shown in FIG. 1 is moved into contact with an 'ob-ject to be lifted, such as a paper roll, the cup assemblies will yield individually whereby rims 14 are in a position most easily to engage the object entirely around the rims and produce a seal.

, Each cup assembly is provided with at least one valve adapter 25 having connections with a vacuum hose 26 which connects with a source of vacuum (not shown). A passageway 27 in the adapter establishes a vacuum connection with the interior of a valve 28 mounted within the confines of rim 14. Adapter 25 projects through an opening '29 provided in equalizer plate '11.

. Valve 28 controls the application of vacuum to the inside of each suction cup assembly. The valve has a plurality of circumferentially distributed slits 35 provided in its sides, which are normally closed. When the suction cup assembly containing the valve is brought into engagement with an object to be lifted, the valve is deformed so that the body thereof is distorted thus to open up one or more of the slits 35. This connects the vacuum source with the mouth opening for the cup, i.e., the region inside the rim of the suction cup assembly, whereby this space has air evacuated therefrom, producing attachment of the suction cup assembly to the object. The valve and related structure is more fully described in a copending application entitled Valve, filed on Sept. 14, 1964, Ser. No. 396,322, now Patent No. 3,291,518.

Considering in more detail the construction of rim 14, and referring now also to FIGS. 2 and 4, forming the outside of the rim is a continuous, elongated casing 40, shown in cross section in FIG. 2 and which, as best illustrated in this figure, comprises opposed side Walls 42, 44 with inner margins of these walls adjacent mounting plate 16. Outer margins of walls 42, 44 face the front of the cup assembly. Joining outer margins of the walls, and integral therewith, is a pad or platform portion 46. The platform portion and side walls together form an outline for the casing which in the embodiment illustrated somewhat resembles the outline of the usual tire casing. The casing may be made of rubber or other elastomer. The rubber selected is fairly stiff, and in this way, when the casing is stressed, deflection along the length of the walls (for instance, vertically in portion 14a shown in FIG. 1) generally is inhibited. The walls, however, can be flexed to bulge outwardly, as indicated by the dashed outline in FIG. 2, in the production of a seal with a load.

Along inner margins of the side walls, and integral with these inner margins, are bead portions 48 which extend continuously along the length of the casing. These bead portions provide a means for securely fastening the side walls along their inner margins to mounting plate 16. Shown fastening the bead portions to the plate is a clamp 50 which, were the clamp to be visible with the cup assembly as shown in FIG. 1, extends in a course generally corresponding to the course of rim 14. In cross section, the clamp has generally a T-shape, as shown in FIG. 2. The clamp may be made of aluminum or other light metal, and shoulders 52 in the clamp overlie and clamp firmly against bea-d portions 48. The clamp is secured in place by means of fasteners or screws 54 extending through bores 56 in the mounting plate and screwed into a suitably threaded bore provided in the clamp.

In the particular embodiment of the invention illustrated, the hollow interior of the casing, i.e., that region located between the side walls, platform portion 46, and the clamp, may be filled with a relatively soft rubber or elastomer material, such as sponge rubber, such rubber filling being shown in FIG. 2 at 58.

Along the front face of rim 14, which comprises an elongated region facing outwardly from the mounting, and extending about the outer periphery of the front face or region, is a sealing element shown at 60 in the modification of FIG. 2. The sealing element is constructed of relatively soft rubber as compared to that in the walls of the casing, and thus is more yieldable than the walls of the casing. This enables suitable flexure in the element so as better to come intimately in contact with an object and produce a seal therewith. In FIG. 2, an extruded rubber strip with elongated parallelly arranged ridges 70 provided along the outer face is shown as the sealing element. The ridges in the modification of FIG. 2 give the strip a generally saw-tooth pattern, in cross section. The elongated ridges being relatively thin and sharp edged are easily flexed to conform to a given shape when pressed against an object, and under the action of atmospheric pressure pushing inwardly against laterally outwardly facing sides of the ridges, the ridges produce a tight seal with the surface of the object. The element may also comprise, as shown in FIG. 3, an elongated soft rubber strip 60a, such as a sponge rubber strip. The element is mounted in a channel 62 formed Within a shoulder portion 64 which extends about the casing.

Extending about the outer face of platform portion or pad 46 of rim 14, disposed inwardly of the sealing strip toward the center of the suction cup mouth opening, is an elongated friction producing contact surface 68. Pad 46 contains elongated channels extending longitudinally along the course of rim 14, shown at 71, whereby ridges are formed that face outwardly from the pad, thus to form this surface. With such ridges, increased traction between the pad and an object being lifted results, the ridges performing much as does the thread on a tire. Extending transversely of pad 68, across these ridges, and communicating with channel 62 containing the sealing element, are transverse grooves or passages 74. These areprovided at spaced intervals along the course of the casing, and in a typical application may be provided, for example at 3 inch modular spacing. When the cup assembly attaches to an object, the sealing element produces a vacuum seal with the surface of the object, and the function of the transverse passages is to enable any vacuum or subatmospheric condition existing within the cup assembly to extend all about the cup to directly adjacent the inside margin of the sealing element. In clamping onto an object, the force with which the object and cup assembly are pressed together is equal to the difference between atmospheric pressure, and the pressure within the cup, multiplied by the area bounded by the seal. With the area bounded by the seal beingthat area bounded by the sealing element, the largest possible area is encompassed, and the greatest possible clamping force results.

As best shown in FIGS. 2 and 3, imbedded within the pad or platform portion of the casing, and also extending in the course that the rim extends, is a thin metal plate 76 shown in cross section in FIGS. 2 and 3. The plate generally lies in a plane which parallels the plane of mounting plate 16. Because the ring is relatively thin, bending of the plate occurs relatively easily in directions normal to plate 11 and mounting plate 16. In directions paralleling the mounting plate, because in this direction the plate may generally be described as being on edge, flexing or bending is inhibited. The function of plate 76 is to prevent snaking and radial inward movement of the rim on producing a vacuum in the space bounded by the rim. Plate 76 still enables rim 14 to give toward and away from mounting plate 16, when seeking to conform to the shape of an object.

In grabbing. a large diameter paper roll, the rim is pressed toward mounting plate 16 at areas located midway between the sides of a cup assembly only slightly more than portions of the rim directly adjacent the sides. With smaller diameter objects, there is a greater amount of give in these central portions of the rim, but a proper seal is still produced.

With the suction cup assemblies, when an object such as a paper roll is lifted, the rims that form the mouths of the cups constitute elements producing a vacuum seal with the object through their sealing strips, as Well as elements which by functional contact with the object transmit to the object the vertical upward force necessary to compensate for the weight of the object being lifted. The frictional contact is produced by the pad portions of the rim held at the front of the cup assemblies through the side walls of the casing. In lifting a load, the casings which are relatively stiff along their lengths are capable of supporting the pad portions without such being shifted downwardly to any great extent by reason of the weight of the load. This double functioning of the rims, i.e., their scaling function, and their force transmitting function, is somewhat unique. The functioning is to be compared with most designs proposed to' date, where separate friction members are provided as integral parts of the back of the cup, producing the frictional contact necessary to lift a load. In order to be able to transmit necessary forces, these separate friction elements are usually relatively stiif, and as a consequence, when such elements are provided, the range of roll sizes that may be handled is strictly limited.

Further discussing the invention, it may be said to be characterized by friction-producing pads resiliently held by the rims in the assembly, in such a manner that the pads may flex toward and away from the backing plate, to compensate for different sizes of objects being carried, but held relatively inflexibly in an up and down direction, so that proper forces may be transmitted through the casings to the object, and also held relatively inflexible from radially inward movement such as tends to result because of atmospheric pressure pushing inwardly against the sides of the casings.

With the assembly shown in FIG. 1, each of the suction cup assemblies functions in the manner specifically described Multiple cup assemblies are provided in order that objects having diflerent ranges of heights may be easily handled. The valves are actuated to produce a vacuum only within those cup assemblies which come up against an object preparatory to picking up the object.

While an embodiment of the invention has been described, changes and variations are possible without departing therefrom. It is desired to cover all modifications of the invention as would be apparent to one skilled in the art, and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In vacuum-operated load grab mechanism, a suction cup assembly comprising a mounting, means defining an open mouth for the suction cup assembly on one side of said mounting, and means for evacuating said month,

said means defining said open mouth comprising an elongated rim on one side of said mounting extending in a continuous course about the mouth opening which rim throughout its length is raised outwardly from the mounting,

said rim along its length having an elongated region facing outwardly from said mounting which includes a sealing strip for producing a vacuum seal with a load, said strip extending about the outer periphery of said region, and elongated friction means for frictionally engaging a load which friction means extends about the inner periphery of said region and is disposed inwardly of said sealing strip, said friction means having an air passage system defined therethrough facilitating the exhaust of air from adjacent the sealing strip,

said combination of sealing strip and friction means for frictionally engaging a load in said rim enabling said rim both to seal onto a load, and at the same time frictionally to engage a load whereby the mass of the load may be supported on said mounting through said rim with raising of the mounting, said rim throughout its length having a yieldable backing common to and thus shared by both the sealing strip and friction means forming said outwardly facingregion, which backing permits movement of said region toward said mounting whereby the rim may deform to handle different load shapes. 2. The vacuum-operated load grab mechanism of claim 1, wherein said elongated friction means comprises an elongated high coefiicient of friction outer surface area of an elongated platform portion, and said air passage system comprises passages extending across the platform portion with inner ends along one side of the platform portion connecting with the mouth of the suction cup assembly and outer ends located adjacent said sealing strip. 3. The vacuum-operated load grab of claim 1, wherein said rim comprises a casing, said casing includes laterally spaced side walls of flexible material forming said backing with outer margins of said side walls spaced away from the mounting, said casing further comprising a platform portion extending between and joining with said side walls adjacent said outer margins, said sealing strip comprises a strip of elastomer material mounted on the platform portion having greater flexibility than the material making up the side walls of the casing, and said friction means comprises an outer surface area for the platform portion disposed inwardly toward the open mouth of the suction cup from the sealing strip.

4. The vacuum-operated load grab mechanism of claim 3, wherein said platform portion of the casing is made' of flexible material, and stiffener means is joined to the platform portion along the length thereof which accommodates flexing of the platform portion toward and away from the mounting but inhibits side-to-side flexing of the platform portion in directions substantially paralleling the mounting.

- 5. A vacuum-operated load grab mechanism comprising a mounting,

an elongated rim, extending in a continuous course which functions as a mouth of a such cup, mounted on one side of said mounting, said rim comprising a casing including a platform portion and laterally spaced side walls of flexible material, said casing side walls having inner margins adjacent said mounting and outer margins spaced away from the mounting in said load grab, said platform portion extending between said side walls and joining said outer margins of the side walls, said platform portion of the casing being of flexible material and having a high coefiicient of friction outer surfacing, said rim further including stiffener means joined to said platform portion adjacent the outer margins of the side walls, accommodating flexing of the platform portion in a direction substantially nor-' mal to the mounting but inhibiting movement of the platform portion in a direction substantially paralleling the mounting and extending toward the center of the suction cup mouth.

References Cited UNITED STATES PATENTS 3,219,379 11/1965 Ames 29464 3,240,525 3/1966 Wood 294-64 FOREIGN PATENTS 382,403 11/1964 Italy.

GERALD M. FORLENZA, Primary Examiner.

G. F. ABRAHAM, Assistant Examiner. 

1. IN VACUUM-OPERATED LOAD GRAB MECHANISM, A SUCTION, CUP ASSEMBLY COMPRISING A MOUNTING, MEANS DEFINING AN OPEN MOUTH FOR THE SUCTION CUP ASSEMBLY ON ONE SIDE OF SAID MOUNTING, AND MEANS FOR EVACUATING SAID MOUTH, SAID MEANS DEFINING SAID OPEN MOUTH COMPRISING AN ELONGATED RIM ON ONE SIDE OF SAID MOUNTING EXTENDING IN A CONTINUOUS COURSE ABOUT THE MOUTH OPENING WHICH RIM THROUGHOUT ITS LENGTH IS RAISED OUTWARDLY FROM THE MOUNTING, SAID RIM ALONG ITS LENGTH HAVING AN ELONGATED REGION FACING OUTWARDLY FROM SAID MOUNTING WHICH INCLUDES A SEALING TRIP FOR PRODUCING A VACUUM SEAL WITH A LOAD, SAID STRIP EXTENDING ABOUT THE OUTER PERIPHERY OF SAID REGION, AND ELONGATED FRICTION MEANS FOR FRICTIONALLY ENGAGING A LOAD WHICH FRICTION MEANS EXTENDS ABOUT THE INNER PERIPHERY OF SAID REGION AND IS DISPOSED INWARDLY OF SAID SEALING STRIP, SAID FRICTION MEANS HAVING AN AIR PASSAGE SYSTEM DEFINED THERETHROUGH FACILITATING THE EXHAUST OF AIR FROM ADJACENT THE SEALING STRIP, SAID COMBINATION OF SEALING STRIP AND FRICTION MEANS FOR FRICTIONALLY ENGAGING A LOAD IN SAID RIM ENABLING SAID RIM BOTH TO SEAL ONTO A LOAD, AND AT THE SAME TIME FRICTIONALLY TO ENGAGE A LOAD WHEREBY THE MASS OF THE LOAD MAY BE SUPPORTED ON SAID MOUNTING THROUGH SAID RIM WITH RAISING OF THE MOUNTING, SAID RIM THROUGHOUT ITS LENGTH HAVING A YIELDABLE BACKING COMMON TO AND THUS SHARED BY BOTH THE SEALING STRIP AND FRICTION MEANS FORMING SAID OUTWARDLY FACING REGION, WHICH BACKING PERMITS MOVEMENT OF SAID REGION TOWARD SAID MOUNTING WHEREBY THE RIM MAY DEFORM TO HANDLE DIFFERENT LOAD SHAPES. 